hunt-sharepoint

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name: hunt-sharepoint description: Hunt Microsoft SharePoint Server (2013/2016/2019/Subscription Edition) on-prem farms — anonymous endpoint enumeration, version disclosure, legacy SOAP login bypass (Authentication.asmx), ToolShell precondition chain (CVE-2025-53770), SafeControl reflection enumeration via Picker.aspx, NTLM Type-2 AD topology disclosure, custom-branding module discovery, EoL farm permanent-CVE-window exploitation, FormDigest anonymous issuance, file-extension blocklist NOT-an-oracle pattern, custom-zone Forms auth bridging on-prem AD. Use when target has SharePoint headers (SPRequestGuid, X-MS-InvokeApp, X-SharePointHealthScore, MicrosoftSharePointTeamServices) or paths (/_layouts/15/, /_vti_bin/, /_api/, /_catalogs/). sources: github, authorized-engagement report_count: 1

Crown Jewel Targets

SharePoint Server (on-prem) is one of the richest enterprise attack surfaces in 2025-2026 bug bounty / red-team work. Three forces converge:

1. End-of-life unpatched code paths. SharePoint Server 2013 reached extended-support EoL on 2023-04-11 (final build 15.0.5545.1000 / KB5002381). Every SharePoint CVE published after that date is permanently unpatched on SP2013 farms. SP2016 reaches EoL 2026-07-14; SP2019 reaches EoL 2026-07-14 (next 2 months as of May 2026); only SP Subscription Edition is currently in active support.
2. CVE-2025-53770 / 53771 "ToolShell" — July 2025 emergency-out-of-band patch chain for SPE / SP2019 / SP2016. The vulnerable code path (anonymous /_layouts/15/ToolPane.aspx?DisplayMode=Edit + anonymous __REQUESTDIGEST + unencrypted ViewState) is present in SP2013 too and will never receive a fix.
3. Custom branded login pages forget legacy SOAP login. /_vti_bin/Authentication.asmx with the Login SOAP op is the SharePoint equivalent of WordPress XMLRPC bypass — accepts native Forms credentials anonymously with no rate limit on most farms even when the branded UI has lockout.

Highest-value SharePoint targets:

• SP2013 farms still on the public internet — every CVE since April 2023 is unpatched. Critical-severity findings.
• Dealer / partner / supplier portals built on SharePoint by enterprise integrators (German VW group, a enterprise system integrator, etc.) — high-impact business data, often nested inside corporate AD trees.
• SharePoint farms with anonymous Forms-auth zones — Authentication.asmx becomes anonymously brute-forceable.
• SharePoint inside corporate AD parent forests — NTLM Type-2 leak (see hunt-ntlm-info) discloses the parent forest membership.
• Telerik-integrated SharePoint installations — additional deserialization sinks on top of SP's own.

Asset types that pay most: internet-reachable SP Server (any version) > SP Online with custom solutions hooks > intranet SP only after VPN compromise.

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Attack Surface Signals

Response-header fingerprints (any one is sufficient — usually multiple co-occur):

SPRequestGuid: <GUID>                           (always — anonymous and authenticated)
X-MS-InvokeApp: 1; RequireReadOnly              (SharePoint web request)
X-SharePointHealthScore: 0                      (SharePoint specific)
SPIisLatency: <ms>                              (SharePoint internal timing)
SPRequestDuration: <ms>                         (SharePoint request duration)
MicrosoftSharePointTeamServices: 15.0.0.0      (often stripped by ELB — but if present, exact version)
X-Forms_Based_Auth_Required: <login URL>        (Forms-auth zone indicator)
X-Forms_Based_Auth_Return_Url: <return URL>     (Forms-auth zone indicator)
X-MSDAVEXT_Error: 917656; Access denied...      (WebDAV extension active)
DAV: 1, 2                                       (WebDAV verbs supported)
Set-Cookie: ASP.NET_SessionId=...               (always — IIS session)
Set-Cookie: FedAuth=...; rtFa=...               (claims-mode auth)
Set-Cookie: WSS_FullScreenMode=...              (SharePoint UI mode)

URL / path fingerprints:

/_layouts/15/                  (SP2013+ layouts root — SP2010 used /_layouts/ without the 15)
/_layouts/14/                  (legacy SP2010 — almost EoL since 2020-10-13)
/_layouts/16/                  (some SP2019 / SPE)
/_vti_bin/                     (FrontPage-RPC + SOAP services)
/_vti_pvt/                     (FrontPage-RPC config — usually 403)
/_vti_inf.html                 (almost always anonymous; contains FPVersion banner)
/_api/                         (modern REST API)
/_api/$metadata                (OData metadata — often anonymous + large)
/_api/contextinfo              (FormDigest issuer — POST only)
/_catalogs/                    (site catalogs: masterpage, wp, lt, theme, solutions)
/_catalogs/users/simple.aspx   (user list — usually 403)
/_layouts/15/start.aspx        (anonymous landing — leaks version)
/_layouts/15/ToolPane.aspx     (web part editor — ToolShell sink)
/_layouts/15/Picker.aspx       (people/list picker — SafeControl recon)
/_layouts/15/download.aspx     (SP-internal file resolver — NOT outbound SSRF)
/_layouts/15/Authenticate.aspx (forms-auth redirector)
/_layouts/15/SignOut.aspx      (logout)
/_layouts/15/error.aspx        (error page — anonymous)
/_layouts/15/AccessDenied.aspx (denied page — anonymous)
/_layouts/15/scriptresx.ashx?culture=en-us&name=core    (resource bundle leak)
/_layouts/15/<Customer>/       (custom-branding modules — see Methodology step 8)
/_vti_bin/Authentication.asmx  (THE legacy login bypass — see hunt-auth-bypass Legacy-Protocol Matrix)
/_vti_bin/SharedAccess.asmx    (often anon-readable)
/_vti_bin/lists.asmx           (auth-required on hardened farms)
/_vti_bin/sites.asmx           (auth-required on hardened farms)
/_vti_bin/sts/                 (Security Token Service — usually 302 to error)
/sites/<name>/                 (site collections)
/personal/<user>/              (MySite / OneDrive-for-Business)

Body signals (in HTML responses):

<meta name="GENERATOR" content="Microsoft SharePoint" />
RegisterSod("...","/_layouts/15/...");                    (Script-on-demand registration)
var g_initUrl='';                                          (start.aspx MDS state)
__REQUESTDIGEST                                            (CSRF token — leaks even to anon if endpoint mis-configured)
__VIEWSTATEENCRYPTED=""                                    (Sign-only ViewState — see hunt-aspnet)
"LibraryVersion":"15.0.X.XXXX"                             (in _api/contextinfo response)
Version:15, webPermMasks:{High:0,Low:                      (in start.aspx body)
HelpWindowKey('WSSEndUser_troubleshooting                  (anonymous error.aspx body)

Tech-stack signals:

• Server: Microsoft-IIS/10.0 + paths starting with /_layouts/15/ → SharePoint 2013/2016/2019/SE
• AWS ELB / ALB in front of SharePoint → cross-node ViewState MAC issues possible (see hunt-aspnet)
• WWW-Authenticate: NTLM on /_api/web/CurrentUser → dual-auth (Forms + NTLM); use hunt-ntlm-info for AD-topology disclosure
• *.test.<customer>.tld → test/staging mirror of production SharePoint; data often mirrored from prod

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Step-by-Step Hunting Methodology

1. Fingerprint the SharePoint version. Build number leaks anonymously through several paths. Map the result to the CVE matrix immediately.

   # Method 1: _vti_inf.html (always anonymous, always present)
   curl -sk "https://target.example/_vti_inf.html"
   # → FPVersion="15.00.0.000" (15.x = SP2013, 16.x = SP2016/2019/SE)
   
   # Method 2: _api/contextinfo POST (anonymous on most farms)
   curl -sk -X POST "https://target.example/_api/contextinfo" \
     -H "Accept: application/json;odata=verbose" \
     | jq -r '.d.GetContextWebInformation.LibraryVersion'
   # → "15.0.5545.1000" (full build number)
   
   # Method 3: /_layouts/15/start.aspx body
   curl -sk "https://target.example/_layouts/15/start.aspx" \
     | grep -oE "15\.[0-9]+\.[0-9]+\.[0-9]+|16\.[0-9]+\.[0-9]+\.[0-9]+"
   

   Map to CVE matrix:

   | Build | Edition | Status | Notable unpatched-after-EoL CVEs | |---|---|---|---| | 15.0.5545.1000 | SP2013 final CU | EoL 2023-04-11 | CVE-2023-29357, CVE-2023-33160/33157/36941, CVE-2024-21318/30043/38023/38024/38094, CVE-2025-53770/53771, CVE-2025-29794 | | 16.0.10416.x | SP2016 | EoL 2026-07-14 | depends on patch level | | 16.0.10417.x+ | SP2019 / SE | active | check Microsoft's monthly Patch Tuesday |

2. Anonymous-endpoint matrix probe. Walk every endpoint in the table below in one pass. Anything anonymous becomes part of the attack chain.

   /_vti_inf.html                                          → version disclosure
   /_layouts/15/start.aspx                                 → version disclosure + session minting
   /_layouts/15/blank.htm                                  → benign anchor for smuggling probes
   /_layouts/15/error.aspx                                 → request-validator behaviour probe
   /_layouts/15/Authenticate.aspx?Source=                  → redirect-chain behaviour
   /_layouts/15/AccessDenied.aspx?Source=                  → redirect-chain behaviour
   /_layouts/15/SignOut.aspx                               → logout — anonymous OK
   /_layouts/15/closeConnection.aspx                       → anonymous OK
   /_layouts/15/scriptresx.ashx?culture=en-us&name=SP.Res  → 35KB localised strings
   /_layouts/15/scriptresx.ashx?culture=en-us&name=core    → 277KB localised strings
   /_layouts/15/ToolPane.aspx?DisplayMode=Edit             → ToolShell precondition (THIS IS THE BIG ONE)
   /_layouts/15/Picker.aspx                                → SafeControl recon (see step 6)
   /_layouts/15/<CustomerName>/pages/login/customlogin.aspx    → custom Forms login (replace `<CustomerName>` with target's customer name)
   /_vti_bin/Authentication.asmx                           → legacy SOAP login — anonymous brute-force (CRITICAL)
   /_vti_bin/Authentication.asmx?WSDL                      → WSDL — confirms Login + Mode ops
   /_vti_bin/SharedAccess.asmx                             → often anonymous
   /_vti_bin/spsdisco.aspx                                 → SP service discovery
   /_api/contextinfo (POST)                                → anonymous FormDigest mint (HIGH)
   /_api/$metadata                                         → 381KB API surface enumeration
   /_api/Search                                            → search service descriptor
   /_api/web/CurrentUser                                   → 401 anon BUT WWW-Authenticate: NTLM leaks AD info (see hunt-ntlm-info)
   

3. Legacy SOAP login bypass via Authentication.asmx. Cross-reference hunt-auth-bypass Legacy-Protocol Matrix. The standard probe:

   # First: confirm Mode = Forms (else this attack vector is N/A)
   curl -sk -X POST "https://target.example/_vti_bin/Authentication.asmx" \
     -H "Content-Type: text/xml; charset=utf-8" \
     -H "SOAPAction: http://schemas.microsoft.com/sharepoint/soap/Mode" \
     -d '<?xml version="1.0"?><soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Body><Mode xmlns="http://schemas.microsoft.com/sharepoint/soap/" /></soap:Body></soap:Envelope>'
   # → <ModeResult>Forms</ModeResult>  ← target is exploitable
   # → <ModeResult>Windows</ModeResult>  ← target uses Windows auth only; this vector N/A
   
   # Then: confirm no rate limit / no lockout (synthetic non-existent users ONLY)
   # Send 10 bursts at "burst-test-synthetic-zzz" with distinct wrong passwords
   # If all 10 return 200 / 431 bytes / uniform timing → confirmed unlimited brute-force surface
   

   Severity: Critical when anonymous + no rate limit + no lockout. Submit as bug-bounty even before demonstrating successful auth — the unbounded credential validation is the bug, not "I cracked X credential."

4. ToolShell precondition chain probe (CVE-2025-53770 class). Three sub-requests:

   # Sub-step a: anonymous GET on ToolPane.aspx
   curl -sk "https://targ